class UserRoleAdd

class UserRoleAdd extends RulesActionBase {
  
  /**
   * Flag that indicates if the entity should be auto-saved later.
   *
   * @var bool
   */
  protected $saveLater = FALSE;
  
  /**
   * Assign role to a user.
   *
   * @param \Drupal\user\UserInterface $user
   *   User object.
   * @param \Drupal\user\RoleInterface[] $roles
   *   Array of UserRoles to assign.
   *
   * @throws \Drupal\rules\Exception\InvalidArgumentException
   */
  protected function doExecute(UserInterface $user, array $roles) {
    foreach ($roles as $role) {
      // Skip adding the role to the user if they already have it.
      if (!$user->hasRole($role->id())) {
        // If you try to add anonymous or authenticated role to user, Drupal
        // will throw an \InvalidArgumentException. Anonymous or authenticated
        // role ID must not be assigned manually.
        try {
          $user->addRole($role->id());
        } catch (\InvalidArgumentException $e) {
          throw new InvalidArgumentException($e->getMessage());
        }
        // Set flag that indicates if the entity should be auto-saved later.
        $this->saveLater = TRUE;
      }
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function autoSaveContext() {
    if ($this->saveLater) {
      return [
        'user',
      ];
    }
    return [];
  }

}